In a company, such as a printing company, which generates a color printed matter, color of the printed matter is periodically measured and color of a printing device that prints the printed matter is adjusted in order to keep quality of the printed matter. In the color adjustment of the printing device, for example, original image data called a color chart is printed by the printing device, and color of each patch in the printed color chart is measured by the colorimetry device. A color shift amount between a measured value of the color of each patch and a target value of the color of each patch is evaluated, and the color of the printing device is adjusted according to an evaluation result.
The color chart includes a plurality of color samples called the patches, each of the plurality of patches is formed by a different color (hue, lightness, and saturation) in many cases, and the plurality of patches are arrayed in a predetermined mode. There are various color charts. For example, there is a color chart having a mode formed by two-dimensionally arraying a plurality of square patches having various colors. In the color chart of the mode, there are various patterns. For example, the patches are arrayed such that a random color arrangement is obtained depending on a content to be evaluated, or the patches are arrayed such that a change in shade between the patches adjacent to each other is decreased like gradation. Not only such color charts are produced by a user using a color chart production tool provided from a manufacturer of the colorimetry device, but also the color charts are provided from a public institution. Thus, in the color chart, there are various patterns depending on a shape, a disposition, and a color scheme of the patch.
On the other hand, the number of colors used in the color adjustment of the printing device increases year by year, the number of patches disposed in the color chart also increases with increasing number of colors, and a size (area) of each patch is small.
Due to such circumstances, it is actually impossible that the colorimetry is performed while a measurement region of the colorimetry device is accurately positioned by hand with respect to each patch. Therefore, there is a demand for an automatic system, in which the position of each patch is automatically measured and the color of each patch is measured while the measurement region of the colorimetry device is automatically matched with the measured position of each patch. In Patent Literature 1, Gretag-Macbeth proposes a method as an example of the automatic system. In the method, a two-dimensional color image of the color chart to be measured is captured, the patch position is calculated by an image processing technique using a computer, and a colorimetry head is moved to the decided patch position to perform the colorimetry on the color chart.
When the colorimetry of each automatically-detected patch position is performed in adjusting the color of the printing device, sometimes the colorimetry device cannot automatically recognize all the patch positions with some cause such as a breakdown (abnormality) of the color chart due to a stain or damage in the actual color chart and the color chart having low contrast between the patches. Therefore, the patch position that cannot automatically be recognized is corrected by hand or another tool, for example, and chart definition information, in which patch attribute information such as information about the patch position and information about the patch color is described, is produced. The colorimetry device measures the color of each patch in the color chart based on the chart definition information. On the other hand, for the color chart in which all the patch positions cannot automatically be recognized, when the patch position is automatically recognized by the colorimetry device in the next color adjustment, there is a high possibility that all the patch positions cannot automatically be recognized again, and resultantly the correction is required again, and man-hour and labor are required.